1. Field
The aspects of the disclosed embodiments generally relate to occupancy detecting sensor switches. More particularly, the aspects of the disclosed embodiments relates to an occupancy detecting sensor switch for controlling a load in a variable manner.
2. Brief Description of Related Developments
Current passive infrared occupancy (“PIR”) sensor devices or switches generally detect apparent motion when an infrared source with one temperature, such as a human or animal, passes in front of an infrared source with another temperature, such as a wall. A PIR sensor measures infrared (IR) light or energy radiating from objects in its field of view, and such sensors are often used as motion detectors. If the amount of infrared energy focused on the sensor of a PIR switch changes, the PIR device will typically switch, or energize another device coupled to the PIR switch, referred to herein as the device under control. The types of devices that might be coupled to, or controlled by a PIR switch, can include, but are not limited to alarms, lights, water systems, fans, heating, ventilation or air-conditioning load, appliances, doors or any other suitably powered device or load.
A PIR switch is generally configured to detect a change in the amount of infrared energy focused on the sensor within a predetermined time period and activate or power the load that is coupled directly or indirectly to the PIR switch. Infrared radiation generally enters through the front of the sensor face. A sensor, or set of sensors, detect a change in IR energy across the sensor. The change in IR energy will trigger the switch to enable or energize the load that is controlled by the switch. The load will then remain on or activated for a pre-determined time period. These types of switches can generally only set a threshold value for the sensor signal outputted by the PIR switch. If the sensor signal exceeds the specified threshold value, the power supply, or circuit under control of the PIR switch is turned on for a predetermined period of time. Otherwise, power is not supplied to the circuit, and the load, such as a light, is kept off. Thus, the function of a typical PIR switch is singular in nature. Either the PIR switch is on or off. Current PIR switches do not analyze the strength of the sensor signal, and also do not respond to a frequency of the induced current, for example, by extending or shortening the “turn-on” time of the device under the control of the PIR switch. Thus, a PIR switch will be activated in the same manner when the detected object is a person or an animal, for example. Similarly, the length of the activation of a PIR switch will be the same whether the infrared energy change is an inadvertent, temporary change, or a change of a longer duration.
It would be advantageous to be able to analyze the strength and frequency of a sensor signal and, in response, variably control the activation of a device under the control of a PIR switch, in order to improve the control, quality, humanization and user friendliness of the PIR switch.